Emilio Emini, a bear of a man, spreads his arms wide and slaps one hand on either side of a 20-ton globe that rotates in a fountain in front of the Merck Research Laboratories in West Point, PA. Etched onto the globe are the seven continents, with stars marking the 10 satellite Merck research labs. “You can stop it,” says Emini, muscling the globe to a halt. He then rotates it himself, showing off the stars in the United States, Canada, Europe and Japan; Africa sinks into the water and then reemerges.

Emini, who headed the Merck R&D team that in 1996 brought to market what has become a bestselling “protease inhibitor” drug against HIV, now runs the company’s large AIDS vaccine research project. The effort’s unprecedented scope and analytical rigor have invigorated the world of research aimed at shackling HIV with a vaccine, which could ultimately provide a far more powerful weapon against AIDS than drugs. While cocktails of anti-HIV drugs have lengthened many lives, no one has been cured, and patients must take several different kinds of pills, on a strict schedule, several times each day. The drugs also are costly, toxic, tricky to prescribe and, if improperly used, can lead to drug-resistant strains of HIV. Compare that to a vaccine, which after a few shots could protect someone from AIDS for years or decades.

It’s far too early to know whether the Merck effort will have any success in stopping HIV and rescuing sub-Saharan Africa and other regions that are drowning in the disease unleashed by the virus, which now has infected 40 million people and killed 25 million more. But the effort signals that big pharmaceutical companies at long last are devoting serious resources to the search for a vaccine, the best hope the world has for ending this epidemic.

Since 1984, the year scientists proved that HIV causes AIDS, drug and biotech companies have tested 50 different anti-HIV vaccines in humans (see “The AIDS Vaccine Pipeline,” p. 65). Only two of those vaccines, however, have made it beyond the first phase in the three-stage human-testing process, and both have had mediocre performances. Indeed, many researchers expect them to fail when put to real-world tests. Part of the problem, critics say, is that the pharmaceutical industry’s investment in such human studies and the experiments leading up to them has been inadequate. Drug companies prefer to invest in treatments, which are much more profitable than vaccines. Only three big pharmaceutical companies other than Merck-Aventis Pasteur, American Home Products and GlaxoSmithKline-even make vaccines. Although each has an AIDS vaccine program, with Aventis Pasteur’s by far the most advanced, all have much smaller programs than Merck’s; and all, unlike Merck, rely heavily on government funding to stay afloat. As a result, cash-strapped biotech firms, many of which have no experience making vaccines, have dominated the field, often pushing forward dubious strategies and hyping small advances in desperate attempts to raise funds from private investors.

Emini’s AIDS vaccine project not only enjoys the full-fledged, deep-pocketed support of a major pharmaceutical company, it also has an unusually strong scientific foundation. Last year, Merck revealed details of an ambitious four-year monkey study more extensive and systematic than any researchers had seen before. In the study, Emini’s team used hundreds of monkeys to analyze and compare several different vaccine approaches, and used the results to choose a novel vaccine strategy, which Merck now is starting to test in humans and hopes to take into large-scale trials in conjunction with the National Institutes of Health.